The present invention relates to a metals recovery apparatus and process for recovering valuable metals from a used electroplating solution and, more particularly, to a metals recovery apparatus where additional plating solution is added at a controlled rate and directional nozzles dictate the plating pattern.
A lot of the electroplating done in this country is done by speciality companies such as electronics manufacturers, eyeglass frame manufacturers, watch makers and similar type industries. In order to cut costs it is a common practice among these speciality companies to recover as much of the valuable metals from used plating solutions as possible. Frequently, the used plating solutions are shipped out of the country to a foreign company for processing since the domestic companies dealing in metals recovery are usually very expensive and their processing has a high turn-around time. The problems of dealing with foreign companies are that shipping costs make the total cost expensive and the turn-around time sometimes runs into several weeks or months. Many of the speciality companies have had to choose between dealing with a high cost and sometimes inefficient domestic company or a foreign company which has a high turn-around time. Some companies have attempted to adapt existing apparatus to their purposes, however, this has only met with limited success. Until the present invention there has not been an inexpensive efficient metals recovery unit which meets the needs of the speciality items industry.
It is well known that electroplating processes can be better carried out at high speeds in agitated plating baths than in non-agitated baths and that vigorously agitated solutions act faster than gently agitated solutions. The reason for such faster rate of deposition is that the turbulence set up within the solution insures constant replacement with fresh solution of the film of electrolyte over the cathode.
It is also known that electroplating processes can be carried out with recirculation of the plating solution between a plating tank and a holding tank. The purpose of the recirculation of the solution is usually to remove metal sediments and the like.
Until the present invention it has not been suggested to vigorously agitate a plating solution between a pair of parallel electrodes in a predetermined pattern and at the same time constantly add untreated plating solution at a controlled rate.
Prior art patents which show agitation of the plating solution and re-circulation of the solution are well known, for example, U.S. Pat. No. 1,431,022, issued to Mumford, discloses such a plating system. In Mumford an electrolytic plating solution is re-circulated between a plating tank and a holding tank, and the solution is agitated between the electrode plates.
In U.S. Pat. No. 2,046,467, issued to Krause, a liquid sterilization apparatus and process is disclosed where an untreated liquid is mixed with a portion of the treated liquid to control the degree of treatment. A liquid to be treated is sprayed against parallel plate electrodes where an oligodynamically active metal is supplied to the liquid by an electric current.
Other prior art patents which show agitation of the plating solution between the electrodes include U.S. Pat. Nos. 3,503,856, Blackmore, and 4,028,272, Bowen et al. The electroposition process of Blackmore discloses a plating tank with spaced electrodes and apertured pipework between the electrodes to direct a jet of electrolyte solution upon the cathodes. It is suggested in Blackmore that better electroplating is achieved by controlling the solution flow rate, aperture size, spacing and distance from the cathode. However, the Blackmore patent like other prior patents does not disclose an inventive process for controlling the solution flow.
The prior art patents in fact are directed to electroplating solution circulating systems which are of general interest to the present invention but do not suggest the present apparatus and process for recovering metals from used plating solutions. It is therefore the purpose of this invention to provide an apparatus and process for recovering metals from electroplating solutions which includes an improved solution recirculation system for controlling the mixing of an untreated solution with a treated solution, and to provide an efficient nozzle arrangement which agitates the solution in a described pattern between a pair of electrodes.